<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<script type="text/javascript">
			/*函数fac用来计算n的阶乘*/
			var y=9;
			function fac (n) {
			  var s=1;
				for(var i=1;i<=n;i++){
					s=s*i;
				}
				return s;
			}
			
			var p=fac(5)/(fac(3)*fac(5-3));
			console.log(p);
		</script>
	</body>
</html>
